Expert now reconsidering cause of San Bruno explosion

June 29, 2011 7:45:19 AM PDT
An expert investigating last year's deadly San Bruno pipeline explosion is now discounting sewer work as the probable cause of the disaster.

In an interview with the San Francisco Chronicle, Robert Nickell said documents that PG&E released to the state just last week have made him reconsider his theory of who is to blame. They show that the utility greatly fluctuated the pressure in the gas pipeline. Nickell says that alone could have created enough stress for the pipeline to fail.

The city of San Bruno and its sewer contractor have claimed that the sewer work was done safely.